Theodolite was one of the earliest augmented reality (AR) apps for iOS when it debuted in 2009 -- in fact Theodolite was pioneering AR technology before "AR" was even a buzzword! In the time since, Theodolite has been used by millions of consumers and professionals in their outdoor adventures and on the job. Now, we've taken the Theodolite concept to Apple Watch by combining a compass, inclinometer, GPS, and maps into one indispensable app that sits on your wrist. We're excited to keep evolving this centuries-old instrument as hardware and software technologies allow the concept to come to new device formats.

On iPhone and iPad, Theodolite uses a viewfinder format, uniting the device sensors (GPS, magnetometer, gyro, accelerometer) and camera. On Apple Watch, Theodolite combines data from these sensors into an AHRS (attitude and heading reference system) layout similar to what you'd see in the glass cockpit of a modern aircraft. This layout allows Theodolite to efficiently display compass bearing (yaw angle), pitch angle, and roll angle in a compact format that works extremely well on a small screen. This information is augmented by latitude, longitude, and altitude from GPS, as well as sun and moon position.

New in Theodolite for Watch version 2 is a map screen and waypoint manager. You can add waypoints on the map or at your current location, and view waypoints on the compass ring to visualize their bearing from your current location.

Theodolite has settings for compass mode (true or magnetic, degrees or mils), distance/altitude units (feet or meters), and position format (decimal degrees, degrees-minutes-seconds, MGRS, USNG, UTM, UTM-B, and Maidenhead Locator System). Users can choose to display an artificial horizon in the center of the app display (tied to pitch and roll) and can set the app's level reference to flat or vertical orientations of the Watch. The app has six color schemes, including two night vision modes - midnight red and luminescent green.

Theodolite for Watch is recommended for Apple Watch Series 5 and later (including Ultra). Apple Watch Series 4 and older do not have a compass sensor and will not show compass data. On older devices, the app uses the device's gyro sensor to measure rotation. You can twist the watch's digital crown to adjust and calibrate the gyro to the sun position, moon position, or a known bearing. Using these references, the "gyro compass" is able to give bearing. The calibration can be repeated as often as desired to give accurate results.

Theodolite reports accuracy from the magnetometer sensor in your Watch. To improve results, operate Theodolite away from magnets, electronics, or sources of electro-magnetic interference, including car dashboards, aircraft cockpits, metal structures, and other devices.

Like all our apps, we plan to continually improve and evolve Theodolite for Watch. Please contact us with feature requests, suggestions, and general feedback. We'd love to hear what you're doing with the app! And if you don't already have Theodolite for your iPhone or iPad, check it out!